The present invention relates generally to gauges, and more particularly, to an apparatus for controlling expansion and contraction occuring in critical components of a gauge during changes of the gauge's temperature.
Production machining or grinding of workpieces involves constant measurement of the workpiece by a gauge whose output often controls the operation of the machining tools. An example of such a gauge is found in U.S. Pat. No. 4,238,886, issued to Brown on Dec. 16, 1980. The gauge is in constant contact with the workpiece so that when the workpiece reaches certain dimensions, the gauge signals the machining tool instructing the tool to adjust its operation such as increasing or decreasing the cutting rate of a workpiece. When proper dimensions of the workpiece are reached, the gauge signals the machining tool to withdraw the cutting tools from the workpiece. Overall quality of the finished product, accurate dimensions, and proper finish require extremely precise gauging.
Changes in the ambient temperature of the gauge's environment affect the temperature of the gauge. Constant contact of the gauge with the workpiece while it is being machined provides a path through which heat is transferred to the gauge. The contact of the cutting tools with the workpiece and the friction that is present between the workpiece and the gauge results in the substantial buildup of heat which, in turn, results in a temperature rise in the gauge.
As the components of the gauge are heated they undergo thermal expansion. This thermal expansion changes the dimensions of the gauge. Expansion of critical components which can result in false readings of changes in the size of the workpiece. As the gauge is in a production run of workpieces, the measured size of the workpiece will vary based on the temperature of the gauge. While a gauge can be calibrated to be accurate at a certain temperature, calibration does not work successfully when the gauge is used throughout a range of temperatures. The present art suffers from having gauges whose accuracy is affected by changes of temperature. Thus, there is a need in the field for a gauge insensitive to dynamic temperature changes.